Recovery procedures between subscriber registers in a telecommunications network

ABSTRACT

The present invention is aimed to provide subscriber registers of a mobile network with higher performance and memory capacity whilst keeping recovery procedures, such as redundancy and restoration procedures, up to reasonable levels and measurements of network performance, signalling load and response time. The present invention provides for a new clustered architecture for subscriber registers, wherein each subscriber register comprises a number of processing blades, each processing blade handling a reduced number of subscribers, and wherein more processing blades can be added without affecting other components in the subscriber register. Failures and unavailability are expected to often occur on a processing blade basis, so that recovery procedures may be carried out for a reduced number of subscribers, thus being completed with lower signalling load and response times. To this end, the present invention also provides for a new method of updating subscriber data between two subscriber registers where at least one follows the clustered architecture.

TECHNICAL FIELD

The present invention generally relates to enhanced recovery proceduresto be carried out between subscriber registers, subscriber databases, orsubscriber serving nodes in a telecommunication network. In particular,the invention relates to subscriber registers, subscriber databases, orsubscriber serving nodes in a mobile network to allow a faster recoveryafter failures therein and. more specifically, to minimize the failuresituation by detecting partial failures involving only a set ofsubscribers and by acting on these partial failures.

BACKGROUND

The high penetration of mobile networks worldwide is now an irrefutablefact and the number of subscribers, as well as the traffic load throughthe networks, is expected to continue growing as more and moreattractive services and achievements are available to users of themobile networks.

As the number of subscribers grow up for mobile networks, even of adifferent generation, such as the GSM for a legacy 2^(nd) generationnetwork or the IP Multimedia Subsystem “IMS” under a 3^(rd) generationnetwork, network operators are continuously demanding more performanceand memory capacity, whilst maintaining profitability of their business,for those network nodes supporting huge amounts of subscribers andnetwork data.

For instance, a Home Location Register “HLR” in charge of subscriberdata, including subscription data, service data and location data forsubscribers of a 2^(nd) generation mobile network, and a VisitorLocation Register “VLR” holding subscriber data for subscribers roamingin a VLR area of the 2^(nd) generation mobile network, are candidatenodes to be demanded with as high performance and memory capacity aspossible to support huge amounts of subscriber data. In particular, theVLR may be provided and considered alone, or in combination with aMobile Switching Centre “MSC” serving the subscriber and providing,among others, call-related functions. In operation, the VLR receivesfrom the MSC a message indicating a location updating for a subscriberroaming into a VLR area, the message including and identifier of theMSC, and submits towards the HLR a corresponding location updatingmessage, the message now including an identifier of the VLR. The HLRreceiving such location updating message, stores the received VLRidentifier as location data for the subscriber and returns back to theVLR the own HLR identifier which is stored in the VLR for any furthercommunication. Thus, both HLR having subscriber data for all thesubscribers of a mobile network, and VLR having subscriber data for allthe subscribers roaming in areas controlled by said VLR, which might bealmost all subscribers in crowd population areas, are expected to beprovided with even higher performance and memory capacity.

Likewise, a Home Subscriber Server “HSS” holding subscriber data,including subscription, service and location data for subscribers of theIMS in a 3^(rd) generation network, and a Serving Call Session ControlFunction “S-CSCF”, which is a node assigned for serving the subscriberin the IMS, may be comparable candidate nodes to be demanded with ashigh performance and memory capacity as possible to support huge amountsof subscriber data. In operation, a subscriber accesses the IMS via aProxy Call Session Control Function “P-CSCF”, from where a correspondingregistration message is submitted towards an interrogating Call SessionControl Function “I-CSCF”. The I-CSCF queries the HSS in order to obtaincapabilities required for assigning a serving node for serving thesubscriber. Once such capabilities are received from the HSS, the I-CSCFselects and assigns an S-CSCF suitable for serving the subscriber, andsubmits the registration message towards said S-CSCF. The S-CSCF thensubmits a message towards the HSS indicating to be assigned for servingthe user, the indication including an identifier of said S-CSCF, anobtains from the HSS a user profile, including the subscriber data forthe subscriber, along with an identifier of the HSS. Thus, both the HSShaving subscriber data for all the subscribers of an IMS network, andthe S-CSCF having subscriber data for all the served subscribers in theIMS network, which might still be a significant number of subscribers,are expected to be provided with high performance and memory capacity.

In particular, the location data is traditionally interpreted as anidentifier of the S-CSCF serving the subscriber for the HSS in the IMS;as an identifier of the VLR where the subscriber is roaming for the HLRin the 2^(nd) generation mobile network; and as an identifier of the MSCcurrently serving the subscriber for the VLR in the 2^(nd) generationmobile network.

Apart from the above candidate nodes to be provided with higherperformance and capacity: HLR, VLR, HSS, S-CSCF, other network nodesprovided for redundancy purposes may be clear candidates as well. Forexample, a redundant Home Location Register “R-HLR” holding redundantsubscriber data for subscribers in one or more primary Home locationRegisters of the 2^(nd) generation mobile network, is a network nodepossibly requiring the highest performance and memory capacity,especially, where configured to serve more than one HLR. for redundancypurposes. Generally speaking, a mobile network may be configured withmore than one HLR or HSS, as the case may be. In a first configuration,each HLR or HSS may have a first memory portion for primary subscribershandled therein, and a second portion for redundant subscribers handledin another HLR or HSS, so that such network node may be regarded as aprimary HLR or HSS for own subscribers and as a R-HLR or R-HSS forredundant subscribers handled in a corresponding primary HLR or HSS. Ina second configuration, each primary HLR or HSS includes all its ownsubscribers and there is provided a corresponding mated node, namely anR-HLR or R-HSS, including redundant data for all the subscribers fromthe former. In a still third configuration, there is a unique R-HLR orR-HSS handling redundant subscribers from a number of primary HLR's orHSS's as the case may be.

Amongst other recovery procedures in currently existing 2^(nd) or 3^(rd)generation mobile networks, a so-called Redundancy Procedure in HLR orHSS, as the case may be, assumes that a primary HLR or HSS is configuredwith subscriber data for its own subscribers, whereas an R-HLR or R-HSSis configured with subscriber data for redundant subscribers, which arein fact handled in a primary HLR or HSS. In the following, a redundancyprocedure is explained with reference to an HLR of a 2^(nd) generationmobile network whilst it may be applicable as well for those skilled inthe art to a 3^(rd) generation mobile network and, more particularly, toan HSS of an IMS network. However, in other implementations theassumption may be that only the primary HLR is configured withsubscriber data for the primary subscribers whereas the R-HLR obtainsall the redundant subscriber data once entering into normal operation.

In general and during normal operation, traffic messages are routed bythe network to the HLR where a given subscriber is defined as primary.However, each HLR may accept operations from the network for anysubscriber defined therein. Where a non-permanent subscriber data ischanged in the primary HLR in charge of corresponding subscriber, as aconsequence of any subscriber activities such as a change in thesubscriber location data, said data change is sent from the primary HLRtowards the R-HLR, wherein the changed non-permanent subscriber data isupdated. In a situation where the primary HLR fails, or becomesunavailable to the network, the R-HLR starts handling traffic for allsubscribers in the failing primary HLR. Afterwards, once the failingprimary HLR has recovered from the failure and resumes work, thenon-permanent subscriber data for a huge number of subscribers may benot up-to-date since, depending on how long the failure lasts, a hugeamount of subscriber activities took place with corresponding changes onsubscriber data. In this end, the recovering primary HLR keepsdisconnected from the network until having been updated with informationup-to-date from the R-HLR. Once updated, the primary HLR may enter intooperation and the R-HLR disconnected from the network.

This so-called Redundancy Procedure, as other recovery procedures incurrently existing 2^(nd) or 3^(rd) generation mobile networks, becomesa quite overloading procedure where demands are put by network operatorsto provide network nodes supporting huge amounts of subscribers andsubscriber data and thus presenting a higher performance and memorycapacity, whilst maintaining low prices. More specifically, theprovision of network nodes such as HLR, VLR, HSS, S-CSCF, and R-HLR withhigher performance and memory capacity represents a challenging drawbackfor suppliers wanting to keep the overall network performance,signalling load and response times up to reasonable levels andmeasurements.

Apart from the so-called Redundancy Procedure explained above, otherrecovery procedures such as a Restoration procedure between an HLR and aVLR of a 2^(nd) generation mobile network may also penalize the overallnetwork performance, signalling load and response times up to reasonablelevels and measurements.

Where a HLR in a 2^(nd) generation mobile network, or a HSS in an IMSnetwork, has recovered from a failure situation and comprises subscriberdata which can not be considered up-to-date for a substantial numbersubscribers, and with or without support of the above Redundancyprocedure, such HLR or HSS requires the updating of most significantsubscriber data for all the subscribers as there is no clue of whatsubscriber data may be trustable or not, and for what subscribers. Inthis respect, the subscriber location data is one among the mostsignificant subscriber data for this purpose and may be wrong whereaddressing a previous serving node, namely a previous MSC, VLR orS-CSCF, not currently serving the subscriber due to a newer roaming areainvolving a different MSC or VLR, or a re-assignation of a new S-CSCF tohandle service capabilities not supported by the previous S-CSCF andrequired for a new service invoked by the subscriber. In the following,a restoration procedure is explained with reference to an HLR of a2^(nd) generation mobile network whilst it may be applicable as well forthose skilled in the art to a 3^(rd) generation mobile network and, moreparticularly, to an HSS of an IMS network.

A so-called restoration procedure may start once a failing HLR hasrecovered from a failure and resumes work, and non-permanent subscriberdata, such as the location data, for a huge number of subscribers may benot up-to-date. Such recovered HLR, following a ‘best effort’ approach,sends a reset indication towards all the known VLR's where ownsubscribers are marked to be roaming. Those VLR's receiving such resetindication, which includes an identifier of the HLR having recoveredfrom a failure, search for subscribers marked with said HLR identifierand disconnect such subscribers by withdrawing them from the VLR areaswhere they are roaming in order to force a new location updating thatallows the recovered HLR to get appropriate location data for suchsubscribers.

As for the redundancy procedure and other recovery procedures, therestoration procedure becomes a quite overloading procedure wheredemands are put by network operators to provide network nodes supportinghuge amounts of subscribers and subscriber data and thus presenting ahigher performance and memory capacity, whilst maintaining low prices.In view of this so-called restoration procedure, the provision ofnetwork nodes such as HLR, VLR, HSS, S-CSCF, and R-HLR with higherperformance and memory capacity represents a challenging drawback forsuppliers wanting to keep the overall network performance, signallingload and response times up to reasonable levels and measurements.

SUMMARY

It is an object of the invention to obviate or, at least, minimize someof the above drawbacks, and to provide network nodes for mobile networkoperators, such as HLR, VLR, HSS, S-CSCF, and R-HLR with higherperformance and memory capacity whilst still keeping the overall networkperformance, signalling load and response times up to reasonable levelsand measurements.

To this end, there is provided in accordance with a first aspect of theinvention a clustered subscriber register for holding subscriber datafor subscribers in a mobile network, wherein the subscriber datacomprise subscription data as well as location data for each subscriber.This clustered subscriber register includes:

-   -   an input unit arranged for receiving location data for a        subscriber from a serving node in the mobile network;    -   a plurality of processing blades, each processing blade handling        a number of subscribers and comprising: a storage arranged for        storing subscriber data for the subscriber, and a processor        arranged for processing a course of actions to be taken for the        subscriber depending on subscriber data for the subscriber;    -   a distributor for determining the processing blade currently        handling the subscriber; and    -   an output unit arranged for submitting a subscriber identity for        the subscriber, an identifier of the clustered subscriber        register, and an identifier of the processing blade handling the        subscriber towards a secondary subscriber register in the mobile        network.

This clustered architecture for a subscriber register, wherein eachprocessing blade is in charge of a number of subscribers, allows for aprofitable scalability where more processing blades can be added withoutsubstantially affecting the rest of components in the clusteredsubscriber register. In addition, failures and unavailability areexpected to more frequently occur on a processing blade basis, ratherthan for the whole clustered subscriber register, so that proper actionscan be taken for one or a reduced number of processing blades, insteadof for the whole clustered subscriber register. Bearing in mind thateach processing blade just handles a number of subscribers, the recoveryprocedures can be carried out for an expectedly smaller number ofsubscribers, thus being completed with lower signalling load andresponse times.

In particular, this clustered subscriber register may be useable as aVLR and, in such a case, the input unit is arranged for receiving thelocation data for the subscriber from an MSC currently serving thesubscriber, whereas the output unit is arranged for submitting towards aHLR the subscriber identity for the subscriber, the identifier of theVLR and the identifier of the processing blade handling the subscribertherein. In other words, the clustered subscriber register may act as aVLR receiving location data from the MSC, and submitting its own VLRidentifier and its processing blade identifier as location data for thesubscriber towards the secondary subscriber register, that is, towardsthe HLR. Regarding the HLR, it may be a non-clustered HLR behaving as asecondary subscriber register adapted to inter-work with a clusteredVLR, or it may be a clustered HLR behaving in accordance with thisclustered subscriber register as well.

This clustered subscriber register may be implemented in accordance withembodiments of the invention so that the output unit is further arrangedfor submitting a set of subscriber data along with the subscriberidentity for the subscriber, the identifier of the clustered subscriberregister and the identifier of the processing blade, towards thesecondary subscriber register in the mobile network. This isparticularly interesting for using this clustered subscriber register asa HLR of a 2^(nd) generation mobile network and, in such a case, theinput unit is arranged for receiving location data for the subscriberfrom a VLR currently serving the subscriber; as well as for using thisclustered subscriber register as a HSS of an IMS in a 3^(rd) generationmobile network and, in such a case, the input unit is arranged forreceiving location data for the subscriber from a S-CSCF currentlyassigned for serving the subscriber.

Where the clustered subscriber register acts as a HLR, the output unitmay be arranged for submitting towards an R-HLR, which behaves as thesecondary subscriber register for redundancy purposes, the subscriberidentity and the set of subscriber data for the subscriber, theidentifier of the HLR and the identifier of the processing bladehandling the subscriber in said HLR. This clustered subscriber registeracting as a HLR towards a secondary subscriber register acting as aR-HLR may further comprise a replicator for coordinating with the R-HLRa redundancy procedure for sending subscriber data for those subscribershandled in a processing blade identified by a given identifier.Moreover, the replicator may further comprise a state-transition machineoperating on a processing blade basis to determine the status of theredundancy procedure on course for each processing blade thus helping tokeep the overall network performance, signalling load and response timesup to reasonable levels and measurements where recovery procedures canbe carried out on a processing blade basis.

Where the clustered subscriber register acts as a HLR, the output unitmay be arranged as well for submitting towards a VLR, which behaves asthe secondary subscriber register for holding subscriber data forsubscribers roaming in a VLR area of the mobile network, the subscriberidentity and the set of subscriber data for the subscriber, theidentifier of the HLR and the identifier of the processing bladehandling the subscriber in said HLR. This clustered subscriber register,acting as a HLR towards a secondary subscriber register acting as a VLR,may further comprise a restorer arranged for submitting, after havingrecovered from a failure affecting a processing blade, a resetindication towards those VLRs holding subscriber data for thosesubscribers handled by the recovered blade, the reset indicationincluding the identifier of the clustered subscriber register and theidentifier of the recovered processing blade. This more selective resetallows a faster restoration procedure thus helping to keep the overallnetwork performance, signalling load and response limes up to reasonablelevels and measurements where recovery procedures can be carried out ona processing blade basis.

Where the clustered subscriber register acts as a HSS, the output unitmay be arranged for submitting towards the S-CSCF, which behaves as thesecondary subscriber register for serving the subscriber in the IMS, thesubscriber identity and the set of subscriber data for the subscriber,the identifier of the Home Subscriber Server and the identifier of theprocessing blade handling the subscriber. This clustered subscriberregister, acting as a HSS towards a secondary subscriber register actingas a S-CSCF, may also further comprise a restorer arranged forsubmitting, after having recovered from a failure affecting a processingblade, a reset indication towards those S-CSCFs holding subscriber datafor those subscribers handled by the recovered blade, the resetindication including the identifier of the clustered subscriber registerand the identifier of the recovered processing blade.

Furthermore, the clustered subscriber register, whatever use is given,may be implemented so that the input unit is arranged for receiving anyupgraded operation to process a course of actions for the subscriber,wherein this upgraded operation includes the subscriber identity for thesubscriber and the identifier of the processing blade handling thesubscriber.

In accordance with a second aspect of the invention, there is provided asecondary subscriber register inter-working with the above clusteredsubscriber register for holding subscriber data for subscribers in themobile network, the subscriber data comprising subscription data andlocation data for each subscriber. This secondary subscriber registercomprises:

-   -   an input unit arranged for receiving from the clustered        subscriber register, which holds subscriber data for a        subscriber in the mobile network, a subscriber identity for the        subscriber, an identifier of the clustered subscriber register,        and an identifier of a processing blade handling the subscriber        at the clustered subscriber register;    -   a storage arranged for storing subscriber data and the        subscriber identity for the subscriber, the identifier of the        clustered subscriber register and the identifier of the        processing blade for the subscriber therein; and    -   a processor arranged for processing a course of actions to be        taken for the subscriber depending on the received subscriber        data.

This secondary subscriber register may further comprise an output unitarranged for submitting towards the clustered subscriber register anyupgraded operation to process a course of actions for the subscriber,wherein each upgraded operation includes the subscriber identity for thesubscriber and the identifier of the processing blade handling thesubscriber at the clustered subscriber register.

In particular, where the above clustered subscriber register may beuseable as a VLR, this secondary subscriber register may be useable as aHLR and, in such a case, the input unit is arranged for receiving fromthe VLR the subscriber identity for the subscriber, the identifier ofthe VLR, and the identifier of the processing blade handling thesubscriber as location data for said subscriber.

This secondary subscriber register may be implemented in accordance withembodiments of the invention so that the input unit is arranged forreceiving a set of subscriber data for the subscriber, along with thesubscriber identity for the subscriber, the identifier of the clusteredsubscriber register and the identifier of the processing blade, from theclustered subscriber register in the mobile network. Aligned withcorresponding embodiments for the clustered subscriber register, thisinput unit arranged for receiving a set of subscriber data for thesubscriber is particularly interesting for using this secondarysubscriber register as an R-HLR, as a VLR, or as an S-CSCF.

Where this secondary subscriber register is acting as an R-HLR, theinput unit is arranged for receiving from a clustered HLR the subscriberidentity and the set of subscriber data for the subscriber, theidentifier of said HLR and the identifier of the processing bladehandling the subscriber at said HLR. This secondary subscriber registeracting as an R-HLR may further comprise a replicator for coordinatingwith the clustered HLR a redundancy procedure for receiving subscriberdata for those subscribers handled in a processing blade identified by agiven identifier. Moreover, this replicator may further comprise astate-transition machine operating on a processing blade basis todetermine the status of the redundancy procedure on course for eachprocessing blade thus helping to keep the overall network performance,signalling load and response times up to reasonable levels andmeasurements where recovery procedures can be carried out on aprocessing blade basis by coordinated clustered and secondary subscriberregisters provided in accordance with several aspects of the invention

Where this secondary subscriber register is acting as a VLR, the inputunit is arranged for receiving from a clustered HLR the subscriberidentity and the set of subscriber data for the subscriber, theidentifier of said HLR and the identifier of the processing bladehandling the subscriber at said HLR. Moreover, this secondary subscriberregister acting as a VLR further comprises an output unit arranged forsubmitting location data for the subscriber towards the clustered HLR,this location data comprising an identifier of the subscriber and anidentifier of the VLR. Furthermore, this secondary subscriber registeracting as a VLR may further comprise a restorer arranged for receiving areset indication from the clustered HLR, the reset indication includingthe identifier of the clustered HLR and an identifier of a processingblade recovered after failure. Still further, the restorer may bearranged for initiating a restoration procedure for all the subscriberswith the received identifier of the processing blade in this secondarysubscriber register acting as a VLR.

Where this secondary subscriber register is acting as an S-CSCF, theinput unit is arranged for receiving from a clustered HSS the subscriberidentity and the set of subscriber data for the subscriber preferably inthe form of a user profile, the identifier of said HSS and theidentifier of the processing blade handling the subscriber at said HSS.Moreover, this secondary subscriber register acting as an S-CSCF furthercomprises an output unit arranged for submitting location data for thesubscriber towards the clustered HSS, this location data comprising anidentifier of the subscriber and an identifier of the S-CSCF.Furthermore, this secondary subscriber register acting as an S-CSCF mayfurther comprise a restorer arranged for receiving a reset indicationfrom the clustered HSS, the reset indication including the identifier ofthe clustered HSS and an identifier of a processing blade recoveredafter failure. Still further, the restorer may be arranged forinitiating a restoration procedure for all the subscribers with thereceived identifier of the processing blade in this secondary subscriberregister acting as an S-CSCF.

The above clustered subscriber register may be thus used in cooperationwith the above secondary register so that the clustered subscriberregister incorporates a number of processing blades and provides anidentifier of the processing blade handling a given subscriber, whereasthe secondary subscriber register is arranged for receiving thisidentifier of a processing blade handling the given subscriber, and isarranged for applying recovery procedures on a processing blade basis.

These clustered and secondary subscriber registers are enabled inaccordance with a third aspect of the invention to carry out a method ofupdating subscriber data between said clustered subscriber register andsaid secondary subscriber register, both holding subscriber data forsubscribers in a mobile network, the subscriber data comprisingsubscription data and location data. This method comprises the steps of:

-   -   receiving at the clustered subscriber register location data for        a subscriber from a serving node in the mobile network;    -   determining at a distributor of the clustered subscriber        register a processing blade currently handling the subscriber,        among a plurality of processing blades, each processing blade        handling a number of subscribers and including a storage and a        processor;    -   processing at the processor included in the processing blade a        course of actions to be taken for the subscriber depending on        the subscriber data; and    -   submitting from the clustered subscriber register towards the        secondary subscriber register a subscriber identity for the        subscriber, an identifier of the clustered subscriber register,        and an identifier of the processing blade handling the        subscriber at the clustered subscriber register.

In a first embodiment of the invention, the step of receiving locationdata for the subscriber and the step of submitting identifiers in thismethod may take place in a clustered subscriber register acting as aVLR. In this embodiment, an MSC is the serving node where the locationdata is received from, whereas a HLR is the secondary subscriberregister where the subscriber identity for the subscriber, theidentifier of the VLR and the identifier of the processing blade aresubmitted to.

The above method is particularly advantageous where the step ofsubmitting the subscriber identity, the identifier of the clusteredsubscriber register, and the identifier of the processing blade from theclustered subscriber register towards the secondary subscriber registerincludes a step of obtaining from the storage included in the processingblade a set of subscriber data for the subscriber, and a step ofsubmitting the set of subscriber data for the subscriber.

In a second embodiment of the invention, the step of receiving locationdata for the subscriber and the step of submitting the subscriberidentity and the set of subscriber data for the subscriber, theidentifier of the clustered subscriber register, and the identifier ofthe processing blade in this method may take place in a clusteredsubscriber register acting as a HLR. In this second embodiment, a VLR isthe serving node where the location data is received from, whereas anR-HLR is the secondary subscriber register where the subscriber identityand the set of subscriber data for the subscriber, the identifier of theHLR and the identifier of the processing blade are submitted to.Moreover, the method may further comprise for this second embodiment astep of coordinating between the HLR and the R-HLR a redundancyprocedure for sending subscriber data for those subscribers handled in aprocessing blade identified by a given identifier. Furthermore, in orderto determine the status of the redundancy procedure on course for eachprocessing blade, the method may also comprise a step of operating astate-transition machine on a processing blade basis.

In a third embodiment of the invention, the step of receiving locationdata for the subscriber and the step of submitting the subscriberidentity and the set of subscriber data for the subscriber, theidentifier of the clustered subscriber register, and the identifier ofthe processing blade in this method may take place in a clusteredsubscriber register acting as a HLR. In this third embodiment, a VLR isalso the serving node where the location data is received from, whereassaid VLR is the secondary subscriber register where the subscriberidentity and the set of subscriber data for the subscriber, theidentifier of the HLR and the identifier of the processing blade aresubmitted to. Moreover, the method may further comprise for this thirdembodiment a step of submitting, after having recovered from a failureaffecting a processing blade, a reset indication from the HLR towardsthose VLRs holding subscriber data for those subscribers handled by therecovered blade, the reset indication including the identifier of theHLR and the identifier of the recovered processing blade.

In a fourth embodiment of the invention, the step of receiving locationdata for the subscriber and the step of submitting the subscriberidentity and the set of subscriber data for the subscriber, theidentifier of the clustered subscriber register, and the identifier ofthe processing blade in this method may take place in a clusteredsubscriber register acting as a HSS. In this fourth embodiment, anS-CSCF is the serving node where the location data is received from,whereas said S-CSCF is the secondary subscriber register where thesubscriber identity and the set of subscriber data for the subscriber,the identifier of the HSS and the identifier of the processing blade aresubmitted to. As for the above third embodiment, the method may furthercomprise for this fourth embodiment a step of submitting, after havingrecovered from a failure affecting a processing blade, a resetindication from the HSS towards those S-CSCF holding subscriber data forthose subscribers handled by the recovered blade, the reset indicationincluding the identifier of the HSS and the identifier of the recoveredprocessing blade.

Commonly applicable to the above embodiments, the method may furthercomprise a step of receiving any upgraded operation to process a courseof actions for the subscriber, wherein the upgraded operation includesthe subscriber identity for the subscriber and the identifier of theprocessing blade handling the subscriber in order to more efficientlyreach subscriber data and identify actions to be done for saidsubscriber.

In accordance with a fourth aspect of the invention, there is provided acomputer program, loadable into an internal memory of a computer withinput and output units as well as with a processing unit, the computerprogram comprising executable software adapted to carry out at leastsome of the above method steps when running in the computer. Inparticular, the executable software of this computer program may berecorded in a carrier readable in a computer.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, objects and advantages of the invention will becomeapparent by reading this description in conjunction with theaccompanying drawings, in which:

FIG. 1 is a sequence diagram illustrating an embodiment of a method forupdating the subscriber location between a Visitor Location Register anda Home Location Register, wherein the Home Location Register is aclustered subscriber register in accordance with the invention.

FIG. 2 is a sequence diagram illustrating a method of restoration fromthe Home Location Register towards a plurality of Visitor LocationRegisters known to said Home Location Register, in accordance with anembodiment of the invention.

FIG. 3 is a sequence diagram illustrating an embodiment of a method forupdating the subscriber location between a Mobile Switching Centre and aVisitor Location Register and between the Visitor Location Register anda Home Location Register, wherein the Visitor Location Register is aclustered subscriber register in accordance with the invention.

FIG. 4 is a basic block structure presenting the structural elementsthat a clustered subscriber register comprises in accordance with anembodiment of the invention where acting as a Home Location Register.

FIG. 5 is a basic block diagram illustrating a scenario where clusteredand subscriber registers as well as method of the invention may beapplied in a 2^(nd) generation mobile network.

FIG. 6 is a basic block diagram illustrating a scenario where clusteredand subscriber registers as well as method of the invention may beapplied for an IMS in a 3^(rd) generation mobile network.

FIG. 7 is a basic block structure presenting the structural elementsthat a clustered subscriber register comprises in accordance with anembodiment of the invention where acting as a Visitor Location Register.

FIG. 8 is a sequence diagram illustrating an embodiment of a method forregistering a subscriber in an IMS network, said method including amethod of updating the subscriber location between a Serving CallSession Control Function and a Home Subscriber Server, wherein the HomeSubscriber Server is a clustered subscriber register in accordance withthe invention.

FIG. 9 is a basic block structure presenting the structural elementsthat a clustered subscriber register comprises in accordance with anembodiment of the invention where acting as a Home Subscriber Server.

FIG. 10 is a basic block structure presenting the structural elementsthat a secondary subscriber register comprises in accordance withseveral embodiments of the invention where acting as a Visitor LocationRegister, as a Home Subscriber Server, as a Serving Call Session ControlFunction, as a Home Subscriber Server, or as a redundant Home LocationRegister.

FIG. 11 a-11 d is a sequence diagram illustrating an embodiment of amethod for carrying out a redundancy procedure between a clusteredsubscriber register acting as a Home Location Register and a secondarysubscriber register acting as a redundant Home Location Register, themethod showing how a replica of non-permanent subscriber data is createdin the redundant Home Location Register whilst the primary Home LocationRegister is active, how the redundant Home Location Register handlessubscribers whilst a partial failure occurs in the primary Home LocationRegister, and how the primary Home Location Register becomes activeafter recovering from the partial failure, and once a replica of changednon-permanent subscriber data is created in the primary Home LocationRegister from the redundant Home Location Register.

DETAILED DESCRIPTION

The following describes some preferred embodiments for a method ofupdating subscriber data between a clustered subscriber register and asecondary subscriber register, both holding subscriber data forsubscribers in a mobile network, wherein the subscriber data comprisessubscription data and location data. Apart from this method, thefollowing describes exemplary embodiments of said clustered subscriberregister and said secondary subscriber register in terms of itsrespective structural elements to carry out said method.

In a first embodiment of the invention illustrated in FIG. 3 there isprovided a method of updating subscriber data between a clusteredsubscriber register 40 acting as a VLR, namely a clustered VLR “C-VLR”,and a secondary subscriber register acting as a HLR. This method maypreferably apply in a scenario as basically illustrated in FIG. 5wherein a subscriber 1 attaches via a radio interface a 2^(nd)generation mobile network through a base station not shown for the sakeof simplicity, and reaches a Base Station Centre “BSC” 94 connected withan MSC 92 receiving the subscriber attach.

This method illustrated in FIG. 3 starts with a step S-121 of receivingat the clustered VLR (C-VLR) 40 location data for the subscriber 1 fromthe MSC 92, which is the serving node currently serving the subscriberin the mobile network.

To this end, as illustrated in FIG. 7, the C-VLR 40 includes an inputunit 45 arranged for receiving said location data for the subscriberfrom the MSC 92 in the mobile network. Since this C-VLR comprises aplurality of processing blades 41-43, a particular processing blade 42must be determined for handling this subscriber. This particularprocessing blade 42, as each processing blade 41-43, handles a number ofsubscribers and comprises: a storage 422 arranged for storing subscriberdata for the subscriber 1, and a processor 421 arranged for processing acourse of actions to be taken for the subscriber depending on subscriberdata for said subscriber. To this end, the C-VLR 40 includes adistributor 44, the so-called visitor distribution module “VDM” in thisinstant specification, for determining the processing blade 42 currentlyhandling the subscriber. In particular, this distributor may include acentral processor 441 for carrying out common routines for all theprocessing blades as well as for controlling the availability status foreach processing blade. Then, the input unit 45 internally passes alocation updating message received with location data for the subscriberto the distributor 44, which is the internal entity receiving thelocation data during this step S-121.

The sequence of actions illustrated in FIG. 3 thus continues with a stepS-122 of determining at the distributor 44 of the C-VLR the processingblade 42 for handling the subscriber, and internally passing thelocation updating message received with location data for the subscriberto said processing blade 42. Then, the processing blade receiving suchlocation updating message, processes and stores the new location, namelyan identifier of the MSC 92 currently serving the subscriber, andsubmits in step S-123 towards the secondary subscriber register 30,which in the present embodiment is a HLR holding subscriber data forsubscribers of the mobile network, a subscriber identity for thesubscriber, an identifier of the C-VLR, and an identifier of theprocessing blade handling the subscriber at the C-VLR.

To this end, as illustrated in FIG. 7, the C-VLR, comprises an outputunit 46 an output unit arranged for submitting the subscriber identityfor the subscriber, the identifier of the C-VLR, and the identifier ofthe processing blade handling the subscriber towards a secondarysubscriber register, in this case the HLR, in the mobile network.

On the other hand, the secondary subscriber register 30 illustrated inFIG. 10, which in this first embodiment is a HLR of a 2^(nd) mobilenetwork, comprises an input unit 25 arranged for receiving from theC-VLR the subscriber identity for the subscriber, the identifier of theC-VLR, and the identifier of the processing blade handling thesubscriber at the C-VLR; a storage 21 arranged for storing thesubscriber data 212 and the subscriber identity 211 for the subscriber,the identifier 213 of C-VLR and the identifier 214 of the processingblade for the subscriber therein; and a processor 24 arranged forprocessing a course of actions to be taken for the subscriber dependingon the received subscriber data. In particular, the method described inthis first embodiment may further include a step S-124 of storing at theHLR the location data, namely the identifier of the C-VLR 40 and theidentifier of the processing blade 42, for the subscriber.

This method allows any further action triggered for this subscriber 1towards the C-VLR to include the identifier of the processing blade inorder to more efficiently reach subscriber data and identify actions tobe done for said subscriber. For example, the method described in thisfirst embodiment may further include a step S-125 of submitting from theHLR towards the C-VLR a set of subscriber data for the subscriber alongwith an identifier of the HLR and the identifier of the processing blade42 handling the subscriber in the C-VLR. To this end, the secondarysubscriber register acting as the HLR 30 also comprises an output unit26 arranged for submitting towards the clustered subscriber register,which is now the C-VLR 40. an upgraded operation to process a course ofactions for the subscriber, wherein each upgraded operation includes thesubscriber identity for the subscriber and the identifier of theprocessing blade handling the subscriber at the clustered subscriberregister.

In a second embodiment of the invention partially illustrated in FIG. 1and more specifically illustrated in FIG. 11 b-11 c as part of anexemplary redundancy procedure, there is provided a method of updatingsubscriber data between a clustered subscriber register 10 acting as aHLR, namely a clustered HLR “C-HLR”, and a secondary subscriber registeracting as an R-HLR. This method may preferably apply in a scenario asbasically illustrated in FIG. 5 wherein a subscriber 1 attaches via aradio interface a 2^(nd) generation mobile network through a basestation not shown for the sake of simplicity, reaches a Base StationCentre “BSC” 94 connected with an MSC 92 receiving the subscriberattach, and submitting an update location message towards a VLR 20 incharge of the VLR area where the MSC belongs to. Frequently, the VLR andthe MSC are provided as a combination in a unique network node and arecommonly referred to as an MSC/VLR.

The method under this second embodiment, as illustrated in FIG. 1 andFIG. 11 b, starts with a step S-101 of receiving at the clustered HLR(C-HLR) 10 location data for the subscriber 1 from the VLR (or MSC/VLRas the case might be) 20, which is the serving node currently servingthe subscriber in the mobile network.

To this end, as illustrated in FIG. 4, the C-HLR 10 includes an inputunit 15 arranged for receiving said location data for the subscriberfrom the VLR 20 in the mobile network. Since this C-HLR comprises aplurality of processing blades 11-13, a particular processing blade 11must be determined for handling this subscriber. This particularprocessing blade 11, as each processing blade 11-13, handles a number ofsubscribers and comprises: a storage 112 arranged for storing subscriberdata for the subscriber 1, and a processor 111 arranged for processing acourse of actions to be taken for the subscriber depending on subscriberdata for said subscriber. To this end, the C-HLR 10 includes adistributor 14, the so-called home distribution module “HDM” in thisinstant specification, for determining the processing blade 11 currentlyhandling the subscriber. In particular, this distributor may include acentral processor 141 for carrying out common routines for all theprocessing blades as well as for controlling the availability status foreach processing blade. Then, the input unit 15 internally passes thelocation updating message received with location data for the subscriberto the distributor 14, which is the internal entity receiving thelocation data during this step S-101.

As for the previous embodiment, the sequence of actions illustrated inFIG. 1 and FIG. 11 b thus continues with a step S-102 of determining atthe distributor 14 of the C-HLR the processing blade 11 for handling thesubscriber, and internally passing the location updating messagereceived with location data for the subscriber to said processing blade11. Then, the processing blade receiving such location updating message,processes and stores the new location, namely an identifier of the VLR20 currently serving the subscriber and, as illustrated in FIG. 11 c,submits in step S-166 towards a secondary subscriber register 90, whichin the present embodiment is an R-HLR holding redundant subscriber datafor subscribers of the mobile network, a subscriber identity for thesubscriber, an identifier of the C-HLR, and an identifier of theprocessing blade 11 handling the subscriber at the C-HLR.

To this end, as illustrated in FIG. 4, the C-HLR, comprises an outputunit 16 arranged for submitting the subscriber identity for thesubscriber, the identifier of the C-HLR, and the identifier of theprocessing blade 11 handling the subscriber towards a secondarysubscriber register, in this case the R-HLR 90, in the mobile network.

On the other hand, the secondary subscriber register 90 illustrated inFIG. 10, which in this second embodiment is an R-HLR, comprises an inputunit 25 arranged for receiving from the C-HLR 10 the subscriber identityfor the subscriber, the identifier of the C-HLR, and the identifier ofthe processing blade 11 handling the subscriber at the C-HLR; a storage21 arranged for storing the subscriber data 212 and the subscriberidentity 211 for the subscriber, the identifier 213 of C-HLR and theidentifier 214 of the processing blade for the subscriber therein; and aprocessor 24 arranged for processing a course of actions to be taken forthe subscriber depending on the received subscriber data.

The method described hereinbefore, as well as the structural elementsthat form the clustered and the secondary subscriber registers,especially in respect of the above second embodiment, allow recoveryprocedures such as the so-called redundancy procedure to be carried outfor network nodes such as HLR, VLR, HSS, S-CSCF, and R-HLR with higherperformance and memory capacity whilst keeping the overall networkperformance, signalling toad and response times up to reasonable levelsand measurements.

In the following an exemplary redundancy procedure between a clusteredHLR “C-HLR” and a redundant HLR “R-HLR” as illustrated in FIG. 11 a toFIG. 11 d. The assumption in this exemplary method is that both C-HLRand R-HLR have been configured with the same permanent subscriber datafor those so-called primary subscribers in the C-HLR and for thosecorresponding redundant subscribers in the R-HLR. The non-permanentsubscriber data, such as the subscriber location or other serviceindicators, may be either configured with default values or markedunknown until having adopted a particularly significant value. Once bothC-HLR and R-HLR are operating in the mobile network, they both mayindicate to each with a certain periodicity whether they are in anactive status or not.

The exemplary redundancy procedure illustrated in FIG. 11 a starts witha coordination between the C-HLR 10 and the R-HLR 90 of the redundancyprocedure for sending subscriber data for those subscribers handled ineach processing blade. Such coordination may be initiated by the C-HLRor by the R-HLR. The illustrated exemplary procedure starts when theR-HLR 90 submits during step S-151 a redundancy control “RC” messageindicating its own identifier of secondary subscriber register, namelythe identifier of the R-HLR, along with an indication of being in anactive status, towards the clustered subscriber register, namely theC-HLR 10.

To this end, the input unit 15 in the C-HLR illustrated in FIG. 4cooperates with a replicator 17 to start an internal redundancy controlamongst the different processing blades 11-13 that the C-HLR consistsof. For the sake of simplicity, the input unit is not illustrated in thesequence diagram of FIG. 11 a to 11 b. In an alternative embodiment notillustrated in any drawing, the central processor 141 may include thefunctions of the replicator 17 so that the latter, as an isolatedentity, may be unnecessary.

Again with reference to the method illustrated in FIG. 11 a, thereplicator 17 receiving the redundancy control “RC” message in stepS-151, indicating an active status of the R-HLR 90, sends during stepsS-152, S-154, S-156 towards each processing blade 11-13 an internal RCmessage asking for its individual status. Such query is answered fromeach processing blade during steps S-153, S-155, S-157 indicating itsown identifier of processing blade and its own status, which in thiscase is an active status from all the processing blades. The replicator17 in cooperation with the output unit 16, the latter not shown for thesake of simplicity, sends in step S-158 a corresponding redundancycontrol “RC” message, indicating the own identifier of the C-HLR 10along with an indication of being in an active status, towards the R-HLR90. The sending of this redundancy control indicating an active statusmay be assumed as an implicit trigger for checking the needs for areplica updating, or might start a time gap before triggering suchchecking.

In principle, a replica updating is needed whenever any non-permanentsubscriber data has changed for a subscriber handled in a processingblade. The replica updating is canned out only for changed data in orderto keep up-to-date the contents in the R-HLR, just in case the R-HLR hasto enter into operation following a certain failure in the C-HLR. Asillustrated in FIG. 11 a and FIG. 11 b, the replicator 17 queries theprocessing blades 11-13 during steps S-159, S-161, S-165 whether areplica updating is needed or not. In this exemplary method, theprocessing blade 13 answers in step S-160 that the replica updating isnot needed towards the replicator which marks, this situation. Thisparticular processing blade 13 is not further shown in the followingsequence of actions illustrated in FIG. 11 b to FIG. 11 d since it doesnot participate thereof, and in order to facilitate the drawing offurther interesting network nodes or actions involving the presentnodes.

As receiving the replica updating query during step S-161 in theprocessing blade 12 illustrated in FIG. 11 b, it is found therein thatthe replica in the R-HLR must be updated for a number of subscriberdata. To this end, as illustrated in FIG. 4, the internal processor 121cooperates with the internal storage 122 in the processing blade 12 tocompile a list of subscriber data to be updated in the replica handledin the R-HLR 90.

Regarding the replica updating, and even though changeable non-permanentsubscriber data are candidates to be updated, one may assume thatpermanent subscriber data, which are changeable only by the operator andlikely with provisioning or configuration means, may also be included ina replica updating thus making unnecessary the operator intervention inboth C-VLR and R-HLR.

Once the processing blade 12 has compiled the list of subscriber data tobe updated, it sends in step S-162 such subscriber data along with anidentifier of the C-HLR and an identifier of the processing blade 12towards the R-HLR 90. Such list is used to update the replica in theR-HLR, and an acknowledge message is returned during step S-163 from theR-HLR to the C-HLR including the identifier of the processing blade 12.

To this end, and bearing in mind that the secondary subscriber register,as illustrated in FIG. 10 and claimed by the present invention, isacting as the R-HLR in accordance with this second embodiment, saidR-HLR comprises an input unit 25 arranged for receiving from the C-HLR10 the subscriber identity and the set of subscriber data for eachsubscriber, the identifier of the C-HLR 10 and the identifier of theprocessing blade 12 handling the subscribers; and a storage 21 arrangedfor storing on a subscriber basis the subscriber identity 211 and theset of subscriber data 212 for each subscriber, the identifier 213 ofthe C-HLR 10 and the identifier 214 of the processing blade 12 handlingthe subscribers. In addition, the secondary subscriber register actingas R-HLR may also comprise a replicator 27 for coordinating with theC-HLR 10 the redundancy procedure for receiving subscriber data 212 forthose subscribers handled in a processing blade 12 identified by a givenidentifier 214. As previously commented for the structural elements thatthe C-HLR may comprise, the replicator 27 may be superfluous in thesecondary subscriber register acting as R-HLR if the processor 24 isarranged to carry out a corresponding redundancy control andfunctionality.

Upon receipt in the processing blade 12 in step S-163 of the acknowledgeindicating the replica has been updated in the R-HLR 90, the processingblade indicates the completion of such updating in step S-164 to thereplicator 17. This indication may be advantageous for operating astate-transition machine 171-1 in the replicator to mark a correspondingstatus for such processing blade 12. To this end, the C-HLR illustratedin FIG. 4 may also include a state-transition machine 171-1 included in,or in cooperation with, the replicator 17 or the distributor 14 or thecentral processor 141 included therein.

Back to the sequence of actions illustrate in FIG. 11 b and followingones, one may assume that actions modifying the non-permanent subscriberdata may occur at any time, even during a redundancy procedure. In orderto illustrate such a situation, the sequence of actions in FIG. 11 bcontinues with the reception of a location updating for a subscriber atthe C-HLR 10 during a step S-101 from a VLR 20 currently serving thesubscriber. As previously discussed above when introducing the method ofupdating subscriber data between a clustered subscriber register and asecondary subscriber register, both holding subscriber data forsubscribers in a mobile network, under this second embodiment, suchupdating of location data is received in the distributor 14 incooperation with the input unit 15 of the C-HLR, and internallyforwarded towards the processing blade 11 handling the subscriber. Thenew location data are processed by the local processor 111 and stored instorage 112 in the processing blade 11, and a successful result isreturned back to the VLR 20, either directly during step S-108 asillustrated in FIG. 11 b, or indirectly through the distributor 14during steps S-106 and S-107 as shown in FIG. 1. This particular VLR 20and the distributor 14 are not further shown in the following sequenceof actions illustrated in FIG. 11 c and FIG. 11 d since they do notparticipate thereof, and in order to facilitate the drawing of furtherinteresting actions involving the present nodes.

At this stage different alternatives may be implemented withoutsubstantially departing from the main provisions of the invention. Theupdating of location data for a subscriber in the C-HLR 10 may trigger areplica updating towards the R-HLR 90 in a first alternative not shownin any drawing, or may be simply be marked as ‘replica pending’ so thata further replica updating query from the replicator 17 may trigger suchreplica updating for the new location data towards the R-HLR asillustrated in a second alternative shown in FIG. 11 b.

In this exemplary method, where the above second alternative isfollowed, the replicator 17 internally sends during step S-165 the queryabout needs for replica updating towards the processing blade 11. Thisprocessing blade 11, or rather its processor 111, detects that there isa replica updating and compiles a list of subscriber data to besubmitted towards the R-HLR 90. This list may include, not only thelatest location data updated for one subscriber, but all the subscriberdata modified since a last replica updating took place.

Regarding the replica updating, and depending on the total amount ofsubscriber data to be submitted, the processing blade might need one ormore signalling messages such as a so-called Update Subscriber Data“USD”. Where the submission must be segmented into several USDs forsubmitting all the subscriber data, the identifier of the C-HLR 10 andthe identifier of the processing blade 11 is included in each USD alongwith the subscriber data fitting the signalling message.

As illustrated in FIG. 11 c, and once the list of subscriber data to beupdated is ready, the processing blade 11 in cooperation with the outputunit 16 sends during step S-166 one or more USDs with an amount ofsubscriber data, the identifier of the C-HLR 10 and the identifier ofthe processing blade 11 and advantageously with one end-of-transmissionindicator to advice there is no further USD to submit. Once the replicahas been updated in the R-HLR 90, an acknowledge is returned back to theprocessing blade 11 during step S-167, and the processing bladereceiving such acknowledge sends during step S-168 towards thereplicator 17 an indication of having completed the replica updating. Asfor a previous processing blade, this indication may be advantageous foroperating a state-transition machine 171-1 in the replicator 17 to marka corresponding status for such processing blade 11.

Regarding the coordination of redundancy control and status betweenC-HLR and R-HLR, they do not necessarily have to be synchronized. Eachone may have its own supervision time to indicate to each other its ownstatus.

In this exemplary method, as illustrated in FIG. 11 c, the replicatorstarts a new redundancy control process towards each processing blade11-13. To this end, an internal RC message asking for its individualstatus is submitted towards the processing blade 12 in step S-169 andanswered during step S-170 from the processing blade 12 indicating itsown identifier of processing blade and its own status, which in thiscase is active. This particular processing blade 12 is not further shownin the following sequence of actions illustrated in FIG. 11 d since itdocs not participate thereof, and in order to facilitate the drawing offurther interesting actions involving the present nodes.

The process new redundancy control process continues as illustrated inFIG. 11 c by sending from the replicator 17 during step S-171 aninternal RC message asking for its individual towards the processingblade 11. At this stage, this processing blade 11 may have suffered afailure so that it is not able to answer such message. After areasonable time gap, likely configurable at the replicator 17, or at thecentral processor 141, the replicator 17 may assume the failure, and mayinform about it during step S-173 towards the R-HLR 90, indicating theidentifier of the C-HLR and the identifier of the failing processingblade 11.

This information about the failing processing blade 11 at the C-HLR 10is understood by the R-HLR as an implicit indication to be ready toaccept signalling traffic for subscribers marked with such identifier ofprocessing blade in its local storage 214.

The exemplary method continues as illustrated in FIG. 11 d with thereplicator 17 triggering the switching of routing tables during stepS-174 so that signalling messages addressing the failing processingblade in the C-HLR are forwarded towards the R-HLR. In a preferredalternative solution for this embodiment, the routing tables areincluded in the distributor 14, so that the distributor may identify theprocessing blade in charge of a given subscriber and, as detecting suchsubscriber is handled in a failing processing blade, may forward suchsignalling message towards the R-HLR. In another alternative solution,the routing tables remain in lower protocol layers and are configured ona processing blade basis, so that upon failure in a processing bladebasis, said lower protocol layers are informed and may switch the tablesand inspect signalling messages for determining whether a forwardingtowards the R-HLR should take place or not. This second alternativeseems to be less efficient than the previous one though may be morebackwards compatible than the first one.

One the routing tables have been switched, the R-HLR 90 is ready in stepS-175 for handling subscribers previously in charge of the failingprocessing blade, and thus continues until the failing processing bladerecovers and is operative again.

As illustrated in FIG. 11 d, once the previously failing processingblade 11 is active again, it sends towards the replicator 17 during stepS-176 an RC message indicating its identifier of processing blade aswell as its recovering status. The replicator 17 forwards the RC messageindicating the recovering status along with the identifier of the C-HLRand the identifier of the recovering processing blade 11 during stepS-177 towards the R-HLR 90.

Depending on how long the failure lasted, a number of subscriber datamight have changed whilst the corresponding subscribers were handled bythe R-HLR. Upon recovery of the processing blade 11 in the C-HLR, theR-HLR may need to update the former with the replica contents in itscurrent values. To this end, the R-HLR 90 prepares a list with thechanged subscriber data, mainly non-permanent subscriber data but alsopermanent subscriber data changed by the operator if the failure lastedquite a long time. Then, the R-HLR submits during step S-178 thosesubscriber data that need to be updated in the recovering processingblade 11 of the C-HLR, along with an identifier of the C-HLR and anidentifier of the recovering processing blade 11. As before, one or moresignalling USD messages may be required to this end, each USD includingthe identifier of the C-HLR and the identifier of the recoveringprocessing blade 11.

Once the changed subscriber data have been updated in the recoveringprocessing blade, a successful acknowledge is returned during step S-179from the recovering processing blade 11 to the R-HLR 90. Eventually, theR-HLR may send during step S-180 towards the replicator 17 an indicationof having completed the replica updating. As for a previous processingblade, this indication may be advantageously used for operating againthe state-transition machine 171-1 in the replicator 17 to mark acorresponding active status for such processing blade 11. Thisindication may be understood at the replicator 17 as an implicitindication that the recovering processing blade 11 has recovered and isnow in an active status again. Then, the replicator 17 switches back therouting tables during step S-181 so that signalling messages currentlyaddressing the R-HLR are internally forwarded to the recoveredprocessing blade 11 in the C-HLR. As commented before, in the preferredalternative solution for this embodiment, the routing tables areincluded in the distributor 14, whereas in another alternative solution,the routing tables remain in lower protocol layers. After havingswitched back the routing tables, the recovered processing blade 11, nowin active status takes over in step S-182 its own subscribers again.

At this stage, the interesting pan of a redundancy procedure for thepurpose of the present invention does not require further explanation,but stating that the redundancy control to mutually check the activestatus between both C-HLR and R-HLR continues as previously explained,as well as the internal redundancy control to check the active status ofthe processing blades 11-13 in the C-HLR.

Nevertheless, after having concluded a recovery of a processing bladewithin the above redundancy procedure, and depending on differentimplementation alternatives, there may be a need for a so-calledrestoration procedure. As exemplary commented above, whilst somesubscribers were temporarily served by the R-HLR due to a failure in theprocessing blade primary intended for handling said subscribers, theremight have been a number of location updating from different VLRs for anumber of subscribers. In this situation, the said VLRs might have gotthe identifier of the R-HLR presently handling such subscribers. Afterthe recovery and switching back of routing tables, the identifier of theHLR handling the subscriber stored in each VLR might be the identifierof the R-HLR instead of being the identifier of the C-HLR. Therestoration procedure is an advantageous procedure to ensure thissituation is properly solved and will be further explained in detailafter having discussed a third embodiment of the invention followingthis.

In a third embodiment of the invention illustrated in FIG. 1 andpartially anticipated when discussing the second embodiment illustratedin FIG. 11 b-11 c, there is provided a method of updating subscriberdata between a clustered subscriber register 10 acting as a HLR, namelya clustered HLR “C-HLR”, and a secondary subscriber register acting as aVLR. This method, as for the second embodiment, may preferably apply inthe scenario basically illustrated in FIG. 5 wherein a subscriber 1attaches via a radio interface a 2^(nd) generation mobile networkthrough a base station not shown for the sake of simplicity, thesubscriber reaches a BSC 94 connected with an MSC 92 receiving thesubscriber attach, and submitting an update location message towards aVLR 20 in charge of the VLR area where the MSC belongs to. Frequently,the VLR and the MSC are provided as a combination in a unique networknode and are commonly referred to as an MSC/VLR.

The method in this third embodiment, as illustrated in FIG. 1 andpartially in FIG. 11 b, starts with a step S-101 of receiving at theC-HLR 10 location data for the subscriber 1 from the VLR (or MSC/VLR asthe case might be) 20, which is the serving node currently serving thesubscriber in the mobile network.

To this end, as already commented for the second embodiment and asillustrated in FIG. 4, the C-HLR 10 includes an input unit 15 arrangedfor receiving said location data for the subscriber from the VLR 20 inthe mobile network. Since this C-HLR comprises a plurality of processingblades 11-13, a particular processing blade 11 must be determined forhandling this subscriber. This particular processing blade 11, as eachprocessing blade 11-13, handles a number of subscribers and comprises:storage 112 arranged for storing subscriber data for the subscriber 1,and a processor 111 arranged for processing a course of actions to betaken for the subscriber depending on subscriber data for saidsubscriber. To this end, the C-HLR 10 includes a distributor 14, theso-called HDM in this instant specification, for determining theprocessing blade 11 currently handling the subscriber. In particular,this distributor may include a central processor 141 for carrying outcommon routines for all the processing blades as well as for controllingthe availability status for each processing blade. Then, the input unit15 internally passes the location updating message received withlocation data for the subscriber to the distributor 14, which is theinternal entity receiving the location data during this step S-101.

On the other hand, as illustrated in FIG. 10, the secondary subscriberregister acting as a VLR comprises an output unit 26 arranged forsubmitting location data for the subscriber towards the C-HLR 10, thislocation data including an identifier of the subscriber 1 and anidentifier of the VLR 20. For the purpose of the present invention asubscriber identity and an identifier of a subscriber may be interpretedas equivalent terms, even if nor having always the same value, or ifreplaced at a clustered or secondary register by another subscriberidentity or identifier.

As for the second embodiment, the sequence of actions illustrated inFIG. 1 and FIG. 11 b thus continues for this third embodiment with astep S-102 of determining at the distributor 14 of the C-HLR theprocessing blade 11 for handling the subscriber, and internally passingthe location updating message received with location data for thesubscriber to said processing blade 11.

Then, as shown in FIG. 1, the processing blade 11 receiving suchlocation updating message at the C-HLR, processes and stores the newlocation, namely the identifier of the VLR 20 currently serving thesubscriber, and submits in step S-103 towards the secondary subscriberregister 20, which in this third embodiment is said VLR 20, a subscriberidentity for the subscriber, an identifier of the C-HLR, and anidentifier of the processing blade 11 handling the subscriber at theC-HLR. The submission in the above step S-103 of this method alsoincludes, for this third embodiment, a set of subscriber data along withthe subscriber identity for the subscriber, the identifier of the C-HLR,and the identifier of the processing blade 11, and a so-called InsertSubscriber Data “ISD” message may be used for this purpose.

To this end, as illustrated in FIG. 4, the C-HLR comprises an outputunit 16 arranged for submitting the subscriber identity and the set ofsubscriber data for the subscriber 1, the identifier of the C-HLR, andthe identifier of the processing blade 11 handling the subscribertowards a secondary subscriber register, which in this case is the VLR20, in the mobile network. On the other hand, the secondary subscriberregister 20 illustrated in FIG. 10, which in this third embodiment isthe VLR 20, comprises an input unit 25 arranged for receiving from theC-HLR 10 the subscriber identity and subscriber data for the subscriber,the identifier of the C-HLR, and the identifier of the processing blade11 handling the subscriber at the C-HLR.

The VLR 20 receiving the set of subscriber data and the subscriberidentity for the subscriber, the identifier of the C-HLR, and theidentifier of the processing blade 11, stores them during step S-104 andreturns a successful result during step S-105 towards the processingblade 11 handling the corresponding subscriber at the C-HLR 10.

To this end, the secondary subscriber register 20 illustrated in FIG.10, which in this third embodiment is the VLR 20, comprises a storage 21arranged for storing the subscriber identity 211 and the subscriber data212 for the subscriber, the identifier 213 of C-HLR and the identifier214 of the processing blade 11 for the subscriber at the C-HLR; and aprocessor 24 arranged for processing a course of actions to be taken forthe subscriber depending on the received subscriber data.

The processing blade 11 handling this subscriber may now return asuccessful result for the location updating procedure towards the VLR 20currently serving the subscriber 1, either directly during a step S-108as illustrated in FIG. 11 b, or indirectly through the distributor 14during steps S-106 and S-107 as shown in FIG. 1.

At this stage, once the method for location updating between a C-HLR anda VLR has been discussed in accordance with this third embodiment, therestoration procedure anticipated above can be further discussed indetail.

In principle, the so-called restoration procedure is one amongst therecovery procedures that may be applied after having recovered from afailure situation. This might be the case where a subscriber registerhas suffered a sort of restart and a data dumping has taken place,likely from a reload tape or disk. This might be also the case where anR-HLR has been handling the subscribers of a primary HLR during thefailure, and subscriber data have been changing therein beforerecovering and reloading the primary HLR. In this context, the primaryHLR is understood as the HLR primary intended to hold subscriber datafor a number of such subscribers. Generally speaking, the restorationprocedure may take place where subscriber data stored for subscribers ofa primary HLR in one or more VLRs might have erroneous data, or data notsupposed to be up-to-data.

In particular and for the purpose of the present invention, therestoration procedure may take place where subscriber data stored in oneor more VLRs for subscribers of a processing blade 11 of a C-HLR mighthave erroneous data, or data not supposed to be up-to-data, such as thecase might be where the exemplary redundancy procedure explained abovein relation with the second embodiment has taken place, or where a datareload has taken place after having suffered a sort of restart at aprocessing blade 11 of a C-HLR.

Therefore, an exemplary restoration procedure may take place upondetection of one of the above conditions for a processing blade 11 atthe C-HLR 10. Following the second or third embodiments discussed aboveand as illustrated in FIG. 2, the processing blade 11 determines thoseVLRs 20, 40 which identifier is stored as location data for thesesubscribers handled in said processing blade, and sends a reset messageincluding the identifier of the C-HLR 10 and the identifier of theprocessing blade 11 in respective steps S-111 and S-114 towards saidVLRs 20, 40. In particular, amongst said VLRs there may be a clusteredsubscriber register 40 acting as a clustered VLR “C-VLR” 40, or asecondary subscriber register 20 acting as a non-clustered VLR.

To this end, as FIG. 4 illustrates, the C-HLR may comprise a restorer18, which in cooperation with the processor 111 of the processing blade11 obtains from storage 112 those VLRs 20, 40 which identifier is storedas location data for the subscribers handled in said processing blade,the restorer 18 cooperating with the output unit 16 for submitting thereset message with the identifier of the C-HLR 10 and the identifier ofthe processing blade 11 towards said VLRs 20. 40. Alternatively, therestorer 18 might be unnecessary if the central processor 141 isarranged for carrying out the required steps and functionality of thisrestoration procedure.

The VLRs 20, 40 receiving such reset message in steps S-111 and S-114respectively, initiate its local restoration by firstly searching inrespective steps S-112 and S-115 for subscribers with the receivedidentifier of the C-HLR 10 and the identifier of the processing blade11, and by secondly triggering in respective steps S-113 and S-116 arestoration for such subscribers, which basically may imply thewithdrawal of such subscribers to force a new location updating for themso that current up-to-data subscriber data may be further received fromthe C-HLR 10.

As already commented, these VLRs may be implemented with a clusteredsubscriber register acting as a clustered VLR “C-VLR” 40, or with asecondary subscriber register acting as a non-clustered VLR 20.

Therefore, as illustrated in FIG. 7, a C-VLR 40 may comprise an inputunit 45 cooperating with a restorer 48 for receiving the reset messageand a number of processing blades 41-43, each processing blade 42 havingstorage 422 for storing subscriber data for a number of subscribers anda processor 421 arranged for processing the course of actions to betaken for the subscribers depending on subscriber data for eachsubscriber, in this case, for triggering the withdrawal of subscribersfound with the identifier of the C-HLR 10 and with the identifier of theprocessing blade 11 in the storage 422. Alternatively, the restorer 48might be unnecessary if the central processor 441 carries outcorresponding restoration functions in lieu of the restorer.

On the other hand, a secondary subscriber register 20 acting as anon-clustered VLR 20 may comprise, as illustrated in FIG. 10, an inputunit 25 cooperating with a restorer 28 for receiving the reset messageand a with a processor 24 arranged for processing the course of actionsto be taken for the subscribers depending on subscriber data for eachsubscriber in storage 21. In this case, for triggering the withdrawal ofsubscribers in storage 211 found with the identifier of the C-HLR 10 instorage 213 and with the identifier of the processing blade 11 instorage 214. Alternatively as for other embodiments, the restorer 28might be unnecessary if the central processor 24 carries outcorresponding restoration functions in lieu of the restorer.

As for previous embodiments, the method described hereinbefore for thisthird embodiment, as well as the structural elements that form theclustered and the secondary subscriber registers, especially in respectof the above third embodiment, allow recovery procedures such as theso-called restoration procedure to be carried out for network nodes suchas HLR, VLR, HSS, S-CSCF, and R-HLR with higher performance and memorycapacity whilst keeping the overall network performance, signalling loadand response times up to reasonable levels and measurements.

In a fourth embodiment of the invention illustrated in FIG. 8, there isprovided a method of updating subscriber data between a clusteredsubscriber register 50 acting as a HSS, namely a clustered HSS “C-HSS”,and a secondary subscriber register acting as an S-CSCF. This method maypreferably apply in the scenario basically illustrated in FIG. 6 whereina subscriber 1 attaches via a radio interface an IP Multimedia Subsystem“IMS” of a 3^(rd) generation mobile network through radio premises notshown for the sake of simplicity. The subscriber registers in a P-CSCF98, from where a corresponding registration message is submitted towardsan I-CSCF 96. The I-CSCF 96 queries the HSS 50, 70 in order to obtaincapabilities required for assigning a serving node for serving thesubscriber. Once such capabilities are received from the HSS, the I-CSCFselects and assigns an S-CSCF 60, 80 suitable for serving thesubscriber, and submits the registration message towards said S-CSCF.The S-CSCF then submits a message towards the HSS indicating to beassigned for serving the user, the indication including an identifier ofsaid S-CSCF, an obtains from the HSS a user profile, including thesubscriber data for the subscriber, along with an identifier of the HSS.

The method in this third embodiment, as illustrated in FIG. 8, startswith a step S-131 of registering a subscriber 1 into a P-CSCF 98 of theIMS. The P-CSCF 98 submits the registration message towards the I-CSCF96 in a step S-132. The I-CSCF 96 queries a C-HSS 50 during step S-133to obtain capabilities required for assigning an S-CSCF.

To this end, as illustrated in FIG. 9, the C-HSS 50 includes an inputunit 55 arranged for receiving said query about required capabilitiesfor the subscriber from the I-CSCF 96. Since this C-HSS comprises aplurality of processing blades 51-53, a particular processing blade 52must be determined for handling this subscriber. This particularprocessing blade 52, as each processing blade 51-53, handles a number ofsubscribers and comprises: storage 522 arranged for storing subscriberdata for the subscriber 1, and a processor 521 arranged for processing acourse of actions to be taken for the subscriber depending on subscriberdata for said subscriber. To this end, the C-HSS 50 includes adistributor 54, the so-called DM in this instant specification, fordetermining the processing blade 52 currently handling the subscriber.In particular, this distributor may include a central processor 541 forcarrying out common routines for all the processing blades as well asfor controlling the availability status for each processing blade. Then,the input unit 55 internally passes the query to the distributor 54,which is the internal entity receiving the query during this step S-133.

The sequence of actions illustrated in FIG. 8 thus continues with a stepS-134 of determining at the distributor 54 of the C-HSS 50 theprocessing blade 12 handling the subscriber, and internally passing thequery received for the subscriber to said processing blade 12 duringstep S-135. Then, the processing blade receiving such query, or ratherits local processor 521, returns during step S-136 an identifier of theC-HSS 50 and an identifier of the processing blade 12 along with therequested capabilities.

To this end, the local processor 521 cooperates with an output unit 56for returning these data during the step S-136. Alternatively anddepending on different implementations, the central processor 541 mightalso participate in this step of returning the identifier of the C-HSS50 and the identifier of the processing blade 12 along with therequested capabilities.

In view of the received capabilities, the I-CSCF 96 selects an S-CSCF 60fitting such capabilities and assigns it to the subscriber by forwardingto said S-CSCF 60 during step S-137 the registration message, afterhaving included therein the received identifier of the C-HSS 50 and thereceived identifier of the processing blade 12. Upon receipt of suchregistration message, the S-CSCF 60 informs the C-HSS of being assignedfor serving the subscriber and updates the subscriber location datatherein, namely an identifier of the S-CSCF currently serving thesubscriber, by submitting during step S-138 this location data alongwith the identifier of the C-HSS 50 and the identifier of the processingblade 12.

To this end, the secondary subscriber register 60 acting as the S-CSCF60 in this fourth embodiment, as illustrated in FIG. 10, comprises anoutput unit 26 cooperating with a processor 24 for this submission.

The C-HSS 50 receiving such location updating message, downloads towardsthe S-CSCF a subscriber profile for the subscriber along with theidentifier of the C-HSS 50 and the identifier of the processing blade12, the subscriber profile including the subscriber data for thesubscriber. The S-CSCF 60 receiving the subscriber profile and asubscriber identity for the subscriber, the identifier of the C-HSS, andthe identifier of the processing blade 12, stores them during a step notshown in any drawing, and returns a successful registration resultduring step S-140 towards the I-CSCF 96. the I-CSCF forwarding thisresult during step S-141 towards the P-CSCF, and the latter forwardingit towards the subscriber 1 during step S-142.

To this end, as illustrated in FIG. 9, the C-HSS 50 comprises an inputunit 55 arranged for receiving said location data for the subscriberfrom the S-CSCF 60 and an output unit 56 arranged for submitting thesubscriber identity and subscriber profile for the subscriber, theidentifier of the C-HSS 50, and the identifier of the processing blade12 handling the subscriber towards a secondary subscriber register 60,which in this case is the S-CSCF 60 in the IMS network.

On the other hand, the secondary subscriber register 60 illustrated inFIG. 10, which in this fourth embodiment is the S-CSCF 60, comprises aninput unit 25 arranged for receiving from the C-HSS 50 the subscriberidentity and subscriber profile for the subscriber, the identifier ofthe C-HSS 50, and the identifier of the processing blade 12 handling thesubscriber at the C-HSS; a storage 21 arranged for storing thesubscriber identity 211 and the subscriber data 212 in the subscriberprofile for the subscriber, the identifier 213 of C-HSS and theidentifier 214 of the processing blade 12 for the subscriber at theC-HSS; and a processor 24 arranged for processing a course of actions tobe taken for the subscriber depending on the received subscriber data.

This method described for this fourth embodiment, as well as thestructural elements that form the clustered and the secondary subscriberregisters, allow recovery procedures such as the so-called restorationprocedure to be carried out tor the HSS and the S-CSCF, with higherperformance and memory capacity whilst keeping the overall networkperformance, signalling load and response times up to reasonable levelsand measurements. In this respect, the method in this fourth embodimentmay include a step of submitting, after having recovered from a failureaffecting a processing blade, a reset indication from the C-HSS 50towards those S-CSCF 60, 80 holding subscriber data for thosesubscribers handled by the recovered blade, the reset indicationincluding the identifier of the C-HSS 50 and the identifier of therecovered processing blade. Even though this procedure is notillustrated in any drawing where applying between a C-HSS and a S-CSCF,those skilled in the an would appreciate that the teaching in the abovethird embodiment may also be applied between the C-HSS and the S-CSCF.

Moreover, the clustered subscriber register acting as a C-HSS may have aredundant HSS for holding redundant subscriber data for subscribers holdby the C-HSS. The method in this fourth embodiment may thus include astep of coordinating between the C-HSS 50 and the redundant HSS aredundancy procedure for sending subscriber data for those subscribershandled in a processing blade 51-53 identified by a given identifier.Even though this procedure applying between a C-HSS and a redundant HSSis not illustrated in any drawing, those skilled in the art wouldappreciate that the teaching in the above second embodiment may also beapplied between the C-HSS and the redundant HSS.

Furthermore, the clustered subscriber register may also act as a S-CSCFwherein a similar architecture as the ones illustrated in FIGS. 4, 7 and9 may be applicable to this end.

Therefore, the method described hereinbefore for the four embodiments,as well as the structural elements that build up the clustered and thesecondary subscriber registers, allow recovery procedures such as theso-called redundancy procedure and the so-called restoration procedureto be carried out for network nodes such as HLR, VLR, HSS, S-CSCF, andR-HLR with higher performance and memory capacity whilst keeping theoverall network performance, signalling load and response times up toreasonable levels and measurements.

The invention is described above in respect of several embodiments in anillustrative and non-restrictive manner. Obviously, variations, andcombinations of these embodiments are possible in light of the aboveteachings, and any modification of the embodiments that fall within thescope of the claims is intended to be included therein.

1. A clustered subscriber register holding subscriber data forsubscribers in a mobile network, the subscriber data comprisingsubscription data and location data for each subscriber, the clusteredsubscriber register comprising: an input unit arranged for receivinglocation data for a subscriber from a seizing node in the mobilenetwork; a plurality of processing blades, each processing bladehandling a number of subscribers and comprising: a storage arranged forstoring subscriber data for the subscriber, and a processor arranged forprocessing a course of actions to be taken for the subscriber dependingon subscriber data for the subscriber; a distributor for determining theprocessing blade currently handling the subscriber; and an output unitarranged for submitting a subscriber identity for the subscriber, anidentifier of the clustered subscriber register and an identifier of theprocessing blade handling the subscriber towards a secondary subscriberregister in the mobile network, wherein the input unit is arranged forreceiving from the secondary subscriber register an upgraded operationto process a course of actions for the subscriber, the upgradedoperation including the subscriber identity for the subscriber and theidentifier of the processing blade handling the subscriber.
 2. Theclustered subscriber register of claim 1, wherein the output unit isarranged for submitting, along with the subscriber identity for thesubscriber, the identifier of the clustered subscriber register and theidentifier of the processing blade, a set of subscriber data for thesubscriber towards the secondary subscriber register in the mobilenetwork.
 3. The clustered subscriber register of claim 1, acting as aVisitor Location Register (VLR) holding subscriber data for subscribersroaming in a VLR area of the mobile network, the input unit beingarranged for receiving location data for the subscriber from a MobileSwitching Centre (MSC) currently serving the subscriber, the output unitbeing arranged for submitting to a Home Location Register (HLR) whichholds subscriber data for subscribers of the mobile network, thesubscriber identity for the subscriber, the identifier of the VisitorLocation Register and the identifier of the processing blade handlingthe subscriber therein.
 4. The clustered subscriber register of claim 2,acting as a Home Location Register (HLR) holding subscriber data forsubscribers of the mobile network, the input unit being arranged forreceiving location data for the subscriber from a Visitor LocationRegister (VLR), which is serving the subscriber and holds subscriberdata for subscribers roaming in a VLR area of the mobile network, theoutput unit being arranged for submitting to a redundant Home LocationRegister (R-HLR), which holds redundant subscriber data for subscribersof the mobile network, the subscriber identity and the set of subscriberdata for the subscriber, the identifier of the Home Location Registerand the identifier of the processing blade handling the subscribertherein.
 5. The clustered subscriber register of claim 4, furthercomprising a replicator for coordinating with the redundant HomeLocation Register a redundancy procedure for sending subscriber data forsubscribers handled in a processing blade identified by a givenidentifier.
 6. The clustered subscriber register of claim 5, wherein thereplicator further comprises a state-transition machine operating on aprocessing blade basis to determine the status of the redundancyprocedure on course for each processing blade.
 7. The clusteredsubscriber register of claim 2, acting as a Home Location Registerholding subscriber data for subscribers of the mobile network, the inputunit being arranged for receiving location data for the subscriber froma Visitor Location Register, winch is serving the subscriber and holdssubscriber data for subscribers roaming in a VLR area of the mobilenetwork, the output unit being arranged for submitting to the VisitorLocation Register the subscriber identity and the set of subscriber datafor the subscriber, the identifier of the Home Location Register and theidentifier of the processing blade handling the subscriber therein. 8.The clustered subscriber register or claim 2, acting as a HomeSubscriber Server (HSS) holding subscriber data for subscribers of an IPMultimedia Subsystem (IMS) in the mobile network, the input unit beingarranged for receiving location data for the subscriber from a ServingCall Session Control Function server (S-CSCF), which is assigned forserving the subscriber in the IMS, and the output unit being arrangedfor submitting to said Serving Call Session Control Function server thesubscriber identity and the set of subscriber data for the subscriber,the identifier of the Home Subscriber Server and the identifier of theprocessing blade handling the subscriber.
 9. The clustered subscriberregister of claim 7, further comprising a restorer arranged forsubmitting, after having recovered from a failure affecting a processingblade, a reset indication to secondary subscriber registers holdingsubscriber data for those subscribers handled by the recovered blade,the reset indication including the identifier of the clusteredsubscriber register and the identifier of the recovered processingblade.
 10. A secondary subscriber register arranged for holdingsubscriber data for subscribers in a mobile network, the subscriber datacomprising subscription data and location data for each subscriber, thesecondary subscriber register comprising: an input unit arranged forreceiving from a clustered subscriber register, which holds subscriberdata her a subscriber in the mobile network, a subscriber identity forthe subscriber, an identifier of the clustered subscriber register, andan identifier of a processing blade handling the subscriber at theclustered subscriber register; a storage arranged for storing subscriberdata, the subscriber identity, the identifier of the clusteredsubscriber register and the identifier of the processing blade for thesubscriber; a processor arranged for processing a course of actions tobe taken for the subscriber depending on the received subscriber data;and an output unit arranged for submitting towards the clusteredsubscriber register an upgraded operation to process a course of actionstor the subscriber, the upgraded operation including the subscriberidentity for the subscriber and the identifier of the processing bladehandling the subscriber.
 11. The secondary subscriber register of claim10, wherein the input unit is arranged for receiving a set of subscriberdata for the subscriber, along with the subscriber identity for thesubscriber, the identifier of the clustered subscriber register and theidentifier of the processing blade, from the clustered subscriberregister in the mobile network.
 12. The secondary subscriber register ofclaim 10, acting as a Home Location Register (HLR) holding subscriberdata for subscribers of the mobile network, the input unit beingarranged for receiving from a Visitor Location Register (VLR), which iscurrently serving the subscriber and holds subscriber data forsubscribers roaming in a VLR area of the mobile network, the subscriberidentity for the subscriber, the identifier of the Visitor LocationRegister and the identifier of the processing blade handling thesubscriber.
 13. The secondary subscriber register of claim 11, acting asa redundant Home Location Register (R-HLR) holding redundant subscriberdata for subscribers of the mobile network, the input unit beingarranged for receiving from a clustered Home Location Register, whichholds subscriber data for subscribers of the mobile network, thesubscriber identity and the set of subscriber data for the subscriber,the identifier of the Home Location Register and the identifier of theprocessing blade handling the subscriber.
 14. The secondary subscriberregister of claim 13, further comprising a replicator for coordinatingwith the clustered Home Location Register a redundancy procedure forreceiving subscriber data for those subscribers handled in a processingblade identified by a given identifier.
 15. The secondary subscriberregister of claim 14, wherein the replicator further comprises astate-transition machine operating on a processing blade basis todetermine the status of the redundancy procedure on course for eachprocessing blade.
 16. The secondary subscriber register of claim 11,acting as a Visitor Location Register currently serving the subscriberand holding subscriber data for subscribers roaming in a VLR area of themobile network, further comprising an output unit arranged forsubmitting location data for the subscriber towards a Home LocationRegister, which holds subscriber data for subscribers of the mobilenetwork, and wherein the input unit is arranged for receiving from theHome Location Register the subscriber identity and the set of subscriberdata for the subscriber, the identifier of the Home Location Registerand the identifier of the processing blade handling the subscriber. 17.The secondary subscriber register of claim 11, acting as a Serving CallSession Control Function server (S-CSCF) serving the subscriber in an IPMultimedia Subsystem (IMS) of the mobile network, further comprising anoutput unit arranged for submitting location data for the subscribertowards a Home Subscriber Server (HSS), which holds subscriber data forsubscribers of IMS in the mobile network, and the input unit beingarranged for receiving from the HSS the subscriber identity and the setof subscriber data for the subscriber, the identifier of the HomeSubscriber Server and the identifier of the processing blade handlingthe subscriber.
 18. The secondary subscriber register of claim 16,further comprising a restorer arranged for receiving a reset indicationfrom the clustered subscriber register, the reset indication includingthe identifier of the clustered subscriber register and an identifier ofa processing blade recovered after failure; and arranged for initiatinga restoration procedure for ail the subscribers in the secondarysubscriber register with the received identifier of a processing blade.19. A method of updating subscriber data between a clustered subscriberregister and a secondary subscriber register, both holding subscriberdata for subscribers in a mobile network, the subscriber data comprisingsubscription data and location data, the method comprising the steps of:receiving at the clustered subscriber register location data for asubscriber from a serving node in the mobile network; determining at adistributor of the clustered subscriber register a processing bladecurrently handling the subscriber among a plurality of processingblades, each processing blade handling a number of subscribers andincluding a storage and a processor; processing at the processorincluded in the processing blade, a course of actions to be taken forthe subscriber depending on the subscriber data; submitting from theclustered subscriber register towards the secondary subscriber registera subscriber identity for the subscriber, an identifier of the clusteredsubscriber register, and an identifier of the processing blade handlingthe subscriber at the clustered subscriber register; and receiving atthe clustered subscriber register from the secondary subscriber registeran ungraded operation to process a course of actions for the subscriber,the upgraded operation including the subscriber identity for thesubscriber and the identifier of the processing blade handling thesubscriber.
 20. The method of claim 19, wherein the step of submittingfrom the clustered subscriber register towards the secondary subscriberregister a subscriber identity for the subscriber, an identifier of theclustered subscriber register, and an identifier of the processing bladeincludes a step of obtaining from the storage in the processing blade aset of subscriber data far the subscriber, and a step of submitting theset of subscriber data for the subscriber.
 21. The method of claim 19,wherein the step of receiving location data for the subscriber takesplace at a Visitor Location Register (VLR) holding subscriber data forsubscribers roaming in a VLR area of the mobile network, the locationdata for the subscriber being submitted from a Mobile Switching Centre(MSC) currently serving the subscriber, and wherein the step ofsubmitting takes place at the Visitor Location Register towards a HomeLocation Register (HLR), which holds subscriber data for subscribers ofthe mobile network, the submission including the subscriber identity forthe subscriber, the identifier of the Visitor Location Register and theidentifier of the processing blade handling the subscriber therein. 22.The method of claim 20, wherein the step of receiving location data forthe subscriber takes place at a HLR holding subscriber data forsubscribers of the mobile network, the location data for the subscriberbeing submitted from a Visitor Location Register, which is serving thesubscriber and holding subscriber data for subscribers roaming in a VLRarea of the mobile network, the step of submitting taking place at theHLR towards a redundant Home Location Register (R-HLR), which holdsredundant subscriber data for subscribers of the mobile network, thesubmission including the subscriber identity and the set of subscriberdata for the subscriber, the identifier of the Home Location Registerand the identifier of the processing blade handling the subscribertherein.
 23. The method of claim 22, further comprising a step ofcoordinating between the Home Location Register and the R-HLR aredundancy procedure for sending subscriber data for those subscribershandled in a processing blade identified by a given identifier.
 24. Themethod of claim 22, further comprising a step of operating astate-transition machine on a processing blade basis to determine thestatus of the redundancy procedure on course for each processing blade.25. The method of claim 20, wherein the step of receiving location datafor the subscriber takes place at a Home Location Register holdingsubscriber data for subscribers of the mobile network, the location datafor the subscriber being submitted from a Visitor Location Register,which is serving the subscriber and holding subscriber data forsubscribers roaming in a VLR area of the mobile network, the step ofsubmitting taking place at the HLR towards the Visitor LocationRegister, the submission including the subscriber identity and the setof subscriber data for the subscriber, the identifier of the HomeLocation Register and the identifier of the processing blade handlingthe subscriber therein.
 26. The method of claim 20, wherein the step ofreceiving location data for the subscriber takes place at a HomeSubscriber Server (HSS) holding subscriber data for subscribers of an IPMultimedia Subsystem (IMS) in the mobile network, the location data forthe subscriber being submitted from a Serving Call Session ControlFunction server (S-CSCF), winch is assigned for serving the subscriberin the IMS, the step of submitting taking place at the Home SubscriberServer towards said Serving Call Session Control Function server, thesubmission including the subscriber identity and the set of subscriberdata for the subscriber, the identifier of the Home Subscriber Serverand the identifier of the processing blade handling the subscribertherein.
 27. The method of claim 25, further comprising a step ofsubmitting, after having recovered from a failure affecting a processingblade, a reset indication from the Home Location Register to thoseVisitor Location Registers holding subscriber data for those subscribershandled by the recovered blade, the reset indication including theidentifier of the Home Location Register and the identifier of therecovered processing blade.
 28. The method of claim 26, furthercomprising a step of submitting, after having recovered from a failureaffecting a processing blade, a reset indication from the HomeSubscriber Server towards those Serving Call Session Control Functionservers holding subscriber data for those subscribers handled by therecovered blade, the reset indication including the identifier of theHome Subscriber Server and the identifier of the recovered processingblade.